I studied timing of clamping of the umbilical cord last term in my intrapartum course.
Many providers who practice active management of the 3rd stage of labor will opt to include immediate clamping of the umbilical cord after the birth of the baby, and I see this a whole lot in the hospital setting -- mostly by physicians. Midwives, for the most part, will delay clamping and cutting of the cord until 1-2 minutes, or until the cord actually stops pulsating, which can take several more minutes.
Why the hurry? Why clamp and cut so quickly? It is theorized that in addition to several other actions and interventions, that it reduces the risk for postpartum hemorrhage for the woman.
What about the baby? The baby loses blood volume that rightfully belongs to him or her after the birth. Studies have shown that babies are less likely to have problems with infant anemia if delayed cord clamping occurs. While there is a slightly higher rate of jaundice that requires phototherapy in delayed cord clamping, it's actually considered to be not statistically significant when compared with immediate cord clamping and the risk of jaundice. I have read rates of phototherapy for jaundice running around 3% in immediate cord clamped infants, and 4-5% in delayed cord clamped infants.
Even OB/GYN physicians are coming around to see the benefits of delayed cord clamping. Take a look at these videos from the Academic OBGYN on Grand Rounds.